BASELINE DOCK — Back to Top

Source Code

Copy the HTML, CSS or JavaScript you need for your project.

<button type="button" class="tb-btt-button tb-btt-2043 is-hidden" aria-label="Back to the top of the page" title="Back to Top"><span class="art a43"><span class="a43-line"></span><span class="a43-dock"><b>PAGE TOP</b><span>↗</span></span></span></button>

/* TB-2043 — Back to Top button. */
.tb-btt-2043{--selectedtone:#4b6469;color:#4b6469;position:fixed;right:max(18px,env(safe-area-inset-right));bottom:max(18px,env(safe-area-inset-bottom));z-index:1000;border:0;background:transparent;padding:5px;display:flex;align-items:center;justify-content:center;min-width:48px;min-height:48px;cursor:pointer;font-family:Arial,"Noto Sans JP",sans-serif;line-height:normal;box-sizing:border-box;-webkit-tap-highlight-color:transparent;transition:opacity .24s ease, transform .35s ease,visibility .24s ease}
.tb-btt-2043:is(:focus-visible){outline:2px solid currentColor;outline-offset:4px}
.tb-btt-2043.is-hidden{opacity:0;transform:translateY(10px);visibility:hidden;pointer-events:none}
.tb-btt-2043 *{box-sizing:border-box}
.tb-btt-2043 .art{position:relative;display:flex;align-items:center;justify-content:center;flex-shrink:0}
.tb-btt-2043 .art{color:var(--selectedtone)}
.tb-btt-2043 .a43{width:160px;height:62px;justify-content:flex-start;align-items:flex-end;padding:0 7px 7px}
.tb-btt-2043 .a43-line{position:absolute;bottom:8px;left:0;right:0;height:2px;background:currentColor;opacity:.6;transform-origin:left;transition:transform .5s cubic-bezier(.2,.85,.25,1)}
.tb-btt-2043 .a43-dock{display:flex;align-items:center;justify-content:space-between;gap:14px;position:relative;background:#fffefa;padding:7px 6px 4px;color:#4c6569;min-width:127px;font:700 11px Arial,sans-serif;letter-spacing:1px}
.tb-btt-2043 .a43-dock span{font:20px Arial,sans-serif;line-height:1;transition:transform .45s}
.tb-btt-2043:is(:hover,:focus-visible) .a43-line{transform:scaleX(.79)}
.tb-btt-2043:is(:hover,:focus-visible) .a43-dock span{transform:translateY(-6px)}
@media(prefers-reduced-motion:reduce){.tb-btt-2043,.tb-btt-2043 *, .tb-btt-2043 *::before,.tb-btt-2043 *::after{animation-duration:0.01ms!important;animation-iteration-count:1!important;transition-duration:0.01ms!important}}

/* TB-2043 | Back to Top | No external libraries required. */
(() => {
  'use strict';

  const button = document.querySelector('.tb-btt-2043');
  if (!button) return;

  const reduceMotion = window.matchMedia('(prefers-reduced-motion: reduce)');
  let scheduled = false;

  function update() {
    scheduled = false;
    const visible = window.scrollY > 160;
    button.classList.toggle('is-hidden', !visible);
    button.tabIndex = visible ? 0 : -1;
    button.setAttribute('aria-hidden', String(!visible));
  }

  function requestUpdate() {
    if (scheduled) return;
    scheduled = true;
    requestAnimationFrame(update);
  }

  button.addEventListener('click', () => {
    window.scrollTo({ top: 0, behavior: reduceMotion.matches ? 'auto' : 'smooth' });
  });
  window.addEventListener('scroll', requestUpdate, { passive: true });
  window.addEventListener('resize', requestUpdate, { passive: true });
  update();
})();

How to Use

Insert the HTML button near the end of body, load the CSS, and include JavaScript using defer. Test scrolling, returning to the top, and positioning on mobile.

Use Case

Structured footers and editorial sites

Technical Notes

Keep controls usable on touch devices. Test keyboard focus and reduced-motion preferences.

Mobile：Works with tap and keyboard. Check the lower-right offset against other fixed controls.

Browser：Uses standard HTML, CSS and JavaScript. Install all three together; no external library is required.

Reduced Motion：Reduces transitions and smooth scrolling when reduced motion is requested.